Relaxation oscillation generator



K. SCHLElNGER RELAXATION OSCILLATION GENERATOR Filed Sept. 16, 1933 HIGHPASS FIL TER i F. AMPL/ Hm I E 313- PHASE SHIFTER 45 over the resistance4.

Patented Aug. 24, 1937 UNITED STATES PATENT OFFICE Kurt Schlesinger,Berlin, Germany Application September 16, 1933, Serial No. 689,760 InGermany September 27, 1932 6 Claims.-

When employing glow lamps, and more particularly gas-filled glow lamps,in the known relaxation oscillation generators, the first part of thedischarge takes place so rapidly that the return line on the televisionscreen is not visible.

On the other hand the discharge, on the final part of the dischargecurve, shortly before extinguishing commences to take place, proceedsrelatively slowly. This part of the return line is accordingly visibleon the screen of the Braun tube.

The subject matter of the invention is a meth- 0d of and also anarrangement for enabling this disadvantage to be avoided. The inventionwill be best understood with reference to the accompanying drawing, inwhich Fig. 1 shows the scanned picture area with the course of thereturn line, while Figs. 2 and 3 show exemplary embodiments of theinvention for removing the visible portion of the return line from thepicture area.

In Fig. 1 the upper part of the return line commences with a sharp bendat I and is completely invisible up to the point 2. The lower part ofthe return line owing to the slower wandering velocity over the picturescreen is thickened, and is visible in a disturbing fashion in theimage.

According to the invention, the anode of the glow lamp 3, aftercommencement of the ignimatically in Fig. 2.

In this figure, 3 is a glow lamp, which is preferably operated with agrid of suitable constant, negative bias, and 5 a condenser, which ischarged in the known fashion by the battery 6 To the charging circuitthere is connected a power amplifier l with wattless input. In the anodelead of the amplifier 1 there is provided a retarding member, whichconsists, for example, of the resistance 8 and the condenser 9, and theprimary winding of a step down high-frequency transformer Hi. Thesecondary winding of this transformer, which winding is preferablyconstructed with very low highfrequency impedance, and which transformermay be bridged by a small condenser II, is connected in series with thedischarge circuit. The operation of the arrangement is as follows:

Whereas upon the charging of the tilting condenser 5 the discharge tube3 is .blocked by its control grid in respect of all anode potentialsoccurring, and the high-frequency transformer [0, therefore, is alsoineffective, upon the discharge there is provided in the anode circuitof the connected amplifier tube 1 a high-frequency impulse, which istransmitted very well by the selective transformer. In the retardingmember 8, 8 there is adjusted a delay of such extent as corresponds withthe invisible branch of the return line I, 2 in Fig. 1. It is not untilthis period has elapsed that the high-frequency impulse wave reaches theprimary winding of IO, and produces in the secondary winding a potentialimpulse, the value of which is at least equal to the particularrelaxation condenser potential at the moment, andpreferably is greaterthan the remaining potential, and the phase of which for the firstmoment of the condenser potential is oppositely directed. With suitableselection of this counter-potential it may readily be accomplished thatthe duration of the potential-less condition at the anode of the glowtube suffices for a complete de-ionization of the are. The sub-- sequentdisposal of the secondary winding of the transformer is accordinglyunimportant, and possible oscillation effects thereof are without harm,as the discharge tube, owing to the occurrence of the grid effect, isagain blocked for all anode potentials.

An additional form of embodiment of the idea according to the inventionis illustrated diagrammatically in Fig. 3. The counter-impulse whichblocks the discharge is not derived by reaction from the dischargeoperation itself, but from the synchronization potential, for example asignal potential. This potential is indicated in Fig. 3 by the generator12. For television purposes this potential is necessary in any case forthe operation, and is supplied by the television receiving apparatus tothe relaxation oscillation system. Alternatively, this potential mayalso be taken from the supply potential at the terminals of thecondenser 5. The potential I2 is first conducted over a phase shifter l3, which produces its correct chronological relation to the dischargephase. It then passes to a suitable amplifier l5. This amplifier must bein a position to produce at the impedance resistance 16 connected in thedischarge circuit, for example a small coil, a potential of smallamount, which is sufficient to make the anode potential at the glowdischarge tube 3 for a suflicient length of time equal to zero ornegative. The form of the curve after this point is unimportant. Afterthe amplifier 15 there is preferably connected in series a highpassfilter ll, the reactance of which for the useful frequency of therelaxation oscillation is extremely high.

Naturally, it is quite possible, without departing from the ideaaccording to the invention, also to set forth other circuits forcarrying out the method in the invention, which systems permit ofperformance of the method in simple fashion;

In the method according to the invention the charging condenser is oneach occasion discharged, not down to zero, but merely. down to thepotential corresponding with the point 2 of the return line. This lossof potential, however, may be counter-balanced without difficulty by Themethod increasing the working potential. according to the inventionenables television images to be produced, which are completely free of avisible return line.

I claim:

1. A generator for producing relaxation oscillations comprising aunidirectional source of potential, a charging condenser and a chargingresistance in series, a glow discharge device across said chargingcondenser, an amplifier means hav ing input and output, said input beingconnected across said device and means connected to said output forapplying a potential across said condenser and device counter-acting thecondenser potential during a part of the discharge period of saidcondenser for preventing a complete discharge of said condenser by saidglow discharge device.

2. A generator for producing relaxation oscillations comprising aunidirectional source of potential, a charging condenser and a chargingresistance in series, a glow discharge device across said chargingcondenser, an amplifier having input and output, said input beingconnected across said device and means connected in said output forfeeding back a potential across said condenser and device during a partof the discharge period of said condenser for preventing a completedischarge of said condenser by said glow discharge device.

3. A generator for producing relaxation oscillations comprising aunidirectional source of potential, a charging condenser and a chargingresistance in series, a glow discharge device across said chargingcondenser, a high frequency stepdown transformer, the secondary thereofbeing connected in series with said glow discharge device across. saidcondenser, an amplifier stage having input and output circuits, theinput circuit being connected across said '-device,'the primary of saidtransformer being connected'in the output circuit of said amplifierstageand' phaseretarding means being connected in said output circuit. I

4. A generator for producing relaxation oscillations comprising aunidirectional source of potential, a charging condenser and a chargingresistance in series, a glow discharge device across said chargingcondenser, a high frequency step-down transformer, the secondary thereofbeing connected in series with said glow discharge device across saidcondenser, an amplifier stage having input and output circuits, theinput circuit being connected across said device, the primary of saidtransformer being connected in 'the output circuit of said amplifierstage and phase-retarding means comprising a second resistor and asecond condenser connected in said anode circuit, said high frequencystep-down transformer having a proportion of windings and said phaseretarding means being so dimensioned as to generate a potentialcounter-acting the condenser potential at least to full extent during apart of the discharge period of said charging condenser for, preventingcomplete discharge of said condenser by said discharge device duringsaid part of the discharge period.

5. A generator for producing relaxation 'oscillations comprising aunidirectional source of potential, a charging condenser and a chargingresistance in series, a grid controlled glow discharge device havingcathode and anode elec trodes, said electrodes being connected acrosssaid charging condenser, means for applying a synchronizing potential tothe grid of said discharge device, means for generating an additionalpotential controller by said synchronizing potential, means for applyingsaid additional potential to counter-act the condenser potential duringa part of the discharge period of said condenser for preventing acomplete discharge of said condenser by said glow discharge device.

6. A generator for producing relaxation oscillations comprising aunidirectional source of potential, a charging condenser and a chargingresistance in series, a grid controlled glow discharge device havingcathode and anode electrodes, said electrodes being connected acrosssaid condenser, an amplifier having input and output, a phase shifter,means for applying a synchronizing potential to the grid of saiddischarge device and to the input of said amplifier through said phaseshifter, an impedance connected in series with the electrodes ofsaid"dis-.

charge device and said charging condenser; 'a high frequency filter,said impedance and filter being connected in series in the outputcircuit of said amplifier, said impedance Withholding said synchronizingfrequency from said con-denser, thus generating an additional potentialderived from said synchronizing potential, said additional potentialcounter-acting the condenser potential during a part of the dischargeperiod of said condenser for preventing a complete discharge of saidcondenser by said glow discharge device.

KURT SCHLESINGER.

